Boris Johnson has cited Hong Kong as an example for London to follow in seizing airport growth to maintain economic and financial stature.
The capital's Mayor said "aviation is absolutely key to economic growth" and that Prime Minister David Cameron and Chancellor George Osborne were "kidding themselves" if they thought Britain can maintain its status without it.
Coincidentally, Hong Kong's Chep Lap Kok airport is built on land reclaimed from the sea - an idea Johnson has often mooted to solve London's airport conundrum.
Mr Johnson said: "The Chinese authorities have clearly figured out that aviation is absolutely key to economic growth and they are building a legion of mega-airports that will link them to every market in the world.
"It is hugely impressive yet also devastatingly depressing when you consider that, as long as the vision for aviation in the UK remains steadfastly wedded to Heathrow or a make-do solution, we will not be able to access many of the mega-airports opening here or in the many other dynamic economies building new airfields around the globe.
Mr Johnson wants a four-runway airport either built in the Thames Estuary on an island reclaimed from the sea - the so-called "Boris island" - or on the Isle of Grain in Kent's Hoo Peninsula.
Another option would involve adding a fourth runway at Stansted.
As officials took Mr Johnson on a tour of Hong Kong's airport they explained that it was built in just six years using expertise from British designers and has since become the world's third biggest international airport.
He said: "There are absolutely no circumstances in which the expansion of Heathrow will be acceptable to London or of long term benefit to the country.
"Ambitious cities like Hong Kong have stolen a march on us and built mega-airports that plug them directly into the global supply chains that we need to be part of.
"They have moved heaven and earth to move their airports away from their major centres of population and for London and the wider UK to remain competitive we also have to build an airport capable of emulating that scale of growth."